262 Professor Deivar [Jan. 16, 



Experiments with Carhon Tubes. 



In order to ascertain whether the formation of hydrocyanic acid 

 and acetylene in the arc was really due to transformations induced by 

 some occult power located in the arc, or was simply the result of the 

 high temperature attained by the carbons, experiments were made 

 in carbon tubes, the arc being merely used as a means of heating. 

 The method of arranging the arc for this experiment is represented 



in Fig. 3. 



Fig. 3. 



A block of lime about 5 inches long by 3 inches thick was drilled 

 horizontally, as shown in the drawing, another hole being drilled so 

 as to meet it in the centre of the mass. 



Tho new bricks used in the Bessemer converters do very well for 

 all the experiments of this description. 



A drilled purified carbon was placed in the horizontal channel and 

 made the positive pole, the negative pole being a solid rod of carbon 

 passing through the vertical aperture. Gases were passed through 

 the positive carbon, and were thus subjected to the intense heat of the 

 walls of the tube, the arc passing outside. 



The walls of the positive carbon were pierced by the arc with 

 great rapidity, not lasting, as a rule, more than fifteen minutes. This 

 action could only be retarded by using thicker carbons, or by rotating 

 the tube. 



The porosity of the carbons, which allowed a constant diffusion of 

 gases through their walls, was a great source of difficulty. 



In order to prove that the temperature in the interior of the 

 carbon tube is higher than that of the oxyhydrogen flame, it is suffi- 

 cient to place in it a few small crystals of diamond, and to maintain 

 a current of hydrogen to prevent oxidation. In a few minutes the 

 diamond is transformed into coke. 



On passing a mixture of three volumes hydrogen and one volume 

 nitrogen thoroughly dried through the positive pole, a large yield of 

 hydrocyanic acid was always obtained, and on using equal volumes 

 of hydrogen and nitrogen the quantity was, if anything, increased. 



Pure dry hydrogen by itself gave a trace of hydrocyanic acid, and 

 a considerable quantity of acetylene. 



